The present invention relates to a fan of the flat type, intended more especially for ventilating electronic circuits.
Fans of this kind, whose axial dimension is very much less than the radial dimension, generally comprise a casing forming a cylindrical duct and carrying in its central part, by means of arms, a support for a motor stator. Fan blades are integral with a rotor rotatably mounted on a shaft integral with the casing. Fixing to a wall is achieved by means of a square flange having holes at the corners for passing a screw there through.
It is important for the same type of fan to be able to be used for suction or blowing. To this end, it is provided with two flanges, one on each side. But such a construction leads to complication and a high manufacturing cost, requiring removal from the mould both in the radial and in the axial directions. There also results high material consumption, relatively high weight and large dimensions.
Efforts have been made to reduce these disadvantages by securing by means of two diamentrically opposite lugs situated in the facial planes of the casing. Thus economy in material is achieved, and at the same time manufacture is simplified, since removal from the mould is purely in the axial direction. But the same fan cannot be used both for suction and for blowing.
The present invention aims at providing a fan whose manufacture remains particularly economical both from the amount of material used and the operating simplicity and which, furthermore, may be used equally for blowing or for suction, while presenting a relatively reduced weight and taking up relatively less space.